Let me start by saying that I'm glad you ported this game to Java, it certainly increases the reach of the game and the number of people who can hack on it. You're also a really organized Java programmer, which makes it a lot easier for other people to build on what you made. With that said, this Java implementation needs a lot of performance improvement. I made some trivial changes on it and benchmarked it at a sign…
If you're interested, I wrote a page to let you script your own AI for 2048 in javascript: xuanji.appspot.com/2048/